Industrial cranes, such as gantry cranes, are used for lifting and transporting large cargo containers and other loads to and from railroad cars, truck trailers and other locations, as well as for lifting and transporting boats. The gantry crane typically has a gantry structure comprising a series of connected beams that span over a large item to be lifted.
Each beam of a gantry crane supports a main hoist and an auxiliary hoist. Both the main hoist and the auxiliary hoist are coupled to the beam by a trolley assembly for effecting lateral movement of the hoist along the beam. Precise positioning of the hoists is important in many lifting applications.
The gantry crane can be configured or utilized in a panel turner application wherein a lift assembly is operably attached to the gantry structure and is designed to lift and manipulate, for example, large prestressed concrete slabs or panels that may weigh many tons apiece. While panel turners for gantry cranes according to the prior art provide a number of advantageous features, they nevertheless have certain limitations.
The present invention is provided to overcome certain of these limitations and other drawbacks of the prior art, and to provide advantages and aspects not provided by prior cranes or panel turners. A full discussion of the features and advantages of the present invention is deferred to the following detailed description, which proceeds with reference to the accompanying drawings.